Multi server setup port redirect

My master ISP3 is running properly with a few servers as child without issues.

I am adding 2 more servers to the list but however the new servers have port redirects so they will not be using the standard ports.
(master has no port redirect)

After adding the new child to the master, I can make changes to the child via ISP3 of master, but however the monitor does not indicate the child as executed the commands. But it has as the websites and config is changing.

I am trying to understand how does the child notify the master that it has executed the command.

Is the master logging into the child via a service or mysql to check if its done?

Or is the child updating the master's mysql database that it has done its work?